Re: [PATCH V2 2/3] xen: scsiback: add LUN of restored domain

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

On 02/17/2015 02:02 AM, Juergen Gross wrote:
> When a xen domain is being restored the LUN state of a pvscsi device
> is "Connected" and not "Initialising" as in case of attaching a new
> pvscsi LUN.
>
> This must be taken into account when adding a new pvscsi device for
> a domain as otherwise the pvscsi LUN won't be connected to the
> SCSI target associated with it.


scsiback_do_add_lun() is being called from scsiback_frontend_changed() 
which eventually sets the state to Connected. Is the added test of
'try' an optimization or is it needed for correctness?

-boris


>
> Signed-off-by: Juergen Gross <jgross@suse.com>
> ---
>   drivers/xen/xen-scsiback.c | 19 ++++++++++++++-----
>   1 file changed, 14 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/xen/xen-scsiback.c b/drivers/xen/xen-scsiback.c
> index 9faca6a..9d60176 100644
> --- a/drivers/xen/xen-scsiback.c
> +++ b/drivers/xen/xen-scsiback.c
> @@ -992,7 +992,7 @@ found:
>   }
>
>   static void scsiback_do_add_lun(struct vscsibk_info *info, const char *state,
> -				char *phy, struct ids_tuple *vir)
> +				char *phy, struct ids_tuple *vir, int try)
>   {
>   	if (!scsiback_add_translation_entry(info, phy, vir)) {
>   		if (xenbus_printf(XBT_NIL, info->dev->nodename, state,
> @@ -1000,7 +1000,7 @@ static void scsiback_do_add_lun(struct vscsibk_info *info, const char *state,
>   			pr_err("xen-pvscsi: xenbus_printf error %s\n", state);
>   			scsiback_del_translation_entry(info, vir);
>   		}
> -	} else {
> +	} else if (!try) {
>   		xenbus_printf(XBT_NIL, info->dev->nodename, state,
>   			      "%d", XenbusStateClosed);
>   	}
> @@ -1060,10 +1060,19 @@ static void scsiback_do_1lun_hotplug(struct vscsibk_info *info, int op,
>
>   	switch (op) {
>   	case VSCSIBACK_OP_ADD_OR_DEL_LUN:
> -		if (device_state == XenbusStateInitialising)
> -			scsiback_do_add_lun(info, state, phy, &vir);
> -		if (device_state == XenbusStateClosing)
> +		switch (device_state) {
> +		case XenbusStateInitialising:
> +			scsiback_do_add_lun(info, state, phy, &vir, 0);
> +			break;
> +		case XenbusStateConnected:
> +			scsiback_do_add_lun(info, state, phy, &vir, 1);
> +			break;
> +		case XenbusStateClosing:
>   			scsiback_do_del_lun(info, state, &vir);
> +			break;
> +		default:
> +			break;
> +		}
>   		break;
>
>   	case VSCSIBACK_OP_UPDATEDEV_STATE:
>